Cardiac arrhythmias present a significant health problem. Cardiac arrhythmias include but are not limited to ventricular tachycardias, supraventricular tachycardias, and atrial fibrillation. Of these, atrial fibrillation is the most common cardiac arrhythmia. It has been estimated that over one million people in the United States alone suffer from atrial fibrillation. The incidence of atrial fibrillation is expected to increase over the next several decades as populations in the United States and Europe trend older because atrial fibrillation tends to become more common with increasing age.
Arrhythmias after cardiac surgery are a major cause of morbidity and mortality. Tolerability of arrhythmia is less in the postoperative period than for similar arrhythmias in the preoperative period. Hemodynamic instability is more likely due to the possibility of myocardial dysfunction. Cardiopulmonary bypass, injury to the conduction system during surgery, metabolic and electrolyte abnormalities, especially hypokalemia and hypomagnesemia, contribute to the increased incidence of postoperative arrhythmias. Stress of the surgery with enhanced sympathetic tone and use of inotropic support are added factors. Delayed arrhythmia can occur due to scar-related re-entry.
Atrial fibrillation can be treated with medication intended to maintain normal sinus rhythm and/or decrease ventricular response rates. Specifically, many of the past attempts have been confined to pharmacotherapy, radiofrequency ablation, use of implantable devices, and related approaches. While drug therapy remains a popular route for reducing some arrhythmic events, there has been recognition that systemic effects are often poorly tolerated. Moreover, there is belief that proarrhythmic tendencies exhibited by many drugs can increase mortality in many situations. It would be desirable to have more effective methods for treating or preventing cardiac arrhythmias.